Django官方文档详览：从入门到高级应用开发

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Django官方文档是Python开发人员学习和使用Django框架的重要参考资料，它提供了全面且详尽的指导。该文档分为两大部分：Django documentation概述和Getting started。在概述部分（1-4节），文档首先介绍了获取帮助的方式，包括官方社区、论坛、邮件列表和Stack Overflow等。接着详细解释了文档的组织结构，让读者了解各个部分的功能和顺序。这部分涵盖了模型层（1.4节）、视图层（1.5节）、模板层（1.6节）和表单处理（1.7节），这些都是Django构建Web应用的核心组件。此外，文档还讨论了Django的开发过程（1.8节），包括如何使用admin工具管理数据，以及安全（1.10节）、国际化和本地化（1.11节）的处理。性能优化（1.12节）和地理框架（1.14节）也是开发者关注的重点，它们提供了关于如何提高应用效率和处理地理位置数据的实用建议。另外，文档还提到了其他核心功能，如通用Web应用工具（1.15节），以及Django作为一个开源项目（1.16节）的背景和贡献者社区。 "Getting started"章节（2章）则针对初学者设计了一系列引导教程，从快速安装指南（2.2节）开始，逐步指导编写第一个Django应用，通过七个步骤（2.3-2.10节）展示了从创建项目到编写视图、模板和模型的全过程。这部分不仅教授基本技能，还引入了可重用应用开发的高级概念（2.11节）。最后，2.12节给出了进一步学习的路径，推荐了一些后续阅读材料，帮助读者持续提升对Django的理解和实践能力。 Django官方文档是一个深入浅出的学习资源，无论你是初识Django的新手还是希望深化理解的老手，都能从中找到所需的信息和支持。通过阅读和实践文档中的内容，开发者可以熟练掌握Django框架，实现高效、安全的Web应用程序开发。

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The philosophy here is that your site is edited by a staff, or a client, or maybe just you – and you don’t want to have to

deal with creating backend interfaces just to manage content.

One typical workﬂow in creating Django apps is to create models and get the admin sites up and running as fast as

possible, so your staff (or clients) can start populating data. Then, develop the way data is presented to the public.

2.1.5 Design your URLs

A clean, elegant URL scheme is an important detail in a high-quality Web application. Django encourages beautiful

URL design and doesn’t put any cruft in URLs, like .php or .asp.

To design URLs for an app, you create a Python module called a URLconf . A table of contents for your app, it contains

a simple mapping between URL patterns and Python callback functions. URLconfs also serve to decouple URLs from

Python code.

Here’s what a URLconf might look like for the Reporter/Article example above:

mysite/news/urls.py

from django.urls import path

from . import views

urlpatterns = [

path('articles/<int:year>/', views.year_archive),

path('articles/<int:year>/<int:month>/', views.month_archive),

path('articles/<int:year>/<int:month>/<int:pk>/', views.article_detail),

]

The code above maps URL paths to Python callback functions (“views”). The path strings use parameter tags to

“capture” values from the URLs. When a user requests a page, Django runs through each path, in order, and stops at

the ﬁrst one that matches the requested URL. (If none of them matches, Django calls a special-case 404 view.) This is

blazingly fast, because the paths are compiled into regular expressions at load time.

Once one of the URL patterns matches, Django calls the given view, which is a Python function. Each view gets

passed a request object – which contains request metadata – and the values captured in the pattern.

For example, if a user requested the URL “/articles/2005/05/39323/”, Django would call the function news.views.

article_detail(request, year=2005, month=5, pk=39323).

2.1.6 Write your views

Each view is responsible for doing one of two things: Returning an HttpResponse object containing the content

for the requested page, or raising an exception such as Http404. The rest is up to you.

Generally, a view retrieves data according to the parameters, loads a template and renders the template with the

retrieved data. Here’s an example view for year_archive from above:

mysite/news/views.py

from django.shortcuts import render

from .models import Article

def year_archive(request, year):

a_list = Article.objects.filter(pub_date__year=year)

context = {'year': year, 'article_list': a_list}

return render(request, 'news/year_archive.html', context)

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This example uses Django’s template system, which has several powerful features but strives to stay simple enough

for non-programmers to use.

2.1.7 Design your templates

The code above loads the news/year_archive.html template.

Django has a template search path, which allows you to minimize redundancy among templates. In your Django

settings, you specify a list of directories to check for templates with DIRS. If a template doesn’t exist in the ﬁrst

directory, it checks the second, and so on.

Let’s say the news/year_archive.html template was found. Here’s what that might look like:

mysite/news/templates/news/year_archive.html

{% extends "base.html" %}

{% block title %}Articles for {{ year }}{% endblock %}

{% block content %}

<h1>Articles for {{ year }}</h1>

{% for article in article_list %}

<p>{{ article.headline }}</p>

<p>By {{ article.reporter.full_name }}</p>

<p>Published {{ article.pub_date|date:"F j, Y" }}</p>

{% endfor %}

{% endblock %}

Variables are surrounded by double-curly braces. {{ article.headline }} means “Output the value of the

article’s headline attribute.” But dots aren’t used only for attribute lookup. They also can do dictionary-key lookup,

index lookup and function calls.

Note {{ article.pub_date|date:"F j, Y" }} uses a Unix-style “pipe” (the “|” character). This is called

a template ﬁlter, and it’s a way to ﬁlter the value of a variable. In this case, the date ﬁlter formats a Python datetime

object in the given format (as found in PHP’s date function).

You can chain together as many ﬁlters as you’d like. You can write custom template ﬁlters. You can write custom

template tags, which run custom Python code behind the scenes.

Finally, Django uses the concept of “template inheritance”. That’s what the {% extends "base.html" %}

does. It means “First load the template called ‘base’, which has deﬁned a bunch of blocks, and ﬁll the blocks with

the following blocks.” In short, that lets you dramatically cut down on redundancy in templates: each template has to

deﬁne only what’s unique to that template.

Here’s what the “base.html” template, including the use of static ﬁles, might look like:

mysite/templates/base.html

{% load static %}

<html>

<head>

<title>{% block title %}{% endblock %}</title>

</head>

<body>

{% block content %}{% endblock %}

</body>

</html>

2.1. Django at a glance 11

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Simplistically, it deﬁnes the look-and-feel of the site (with the site’s logo), and provides “holes” for child templates to

ﬁll. This makes a site redesign as easy as changing a single ﬁle – the base template.

It also lets you create multiple versions of a site, with different base templates, while reusing child templates. Django’s

creators have used this technique to create strikingly different mobile versions of sites – simply by creating a new base

template.

Note that you don’t have to use Django’s template system if you prefer another system. While Django’s template

system is particularly well-integrated with Django’s model layer, nothing forces you to use it. For that matter, you

don’t have to use Django’s database API, either. You can use another database abstraction layer, you can read XML

ﬁles, you can read ﬁles off disk, or anything you want. Each piece of Django – models, views, templates – is decoupled

from the next.

2.1.8 This is just the surface

This has been only a quick overview of Django’s functionality. Some more useful features:

• A caching framework that integrates with memcached or other backends.

• A syndication framework that makes creating RSS and Atom feeds as easy as writing a small Python class.

• More sexy automatically-generated admin features – this overview barely scratched the surface.

The next obvious steps are for you to download Django, read the tutorial and join the community. Thanks for your

interest!

2.2 Quick install guide

Before you can use Django, you’ll need to get it installed. We have a complete installation guide that covers all

the possibilities; this guide will guide you to a simple, minimal installation that’ll work while you walk through the

introduction.

2.2.1 Install Python

Being a Python Web framework, Django requires Python. See What Python version can I use with Django? for details.

Python includes a lightweight database called SQLite so you won’t need to set up a database just yet.

Get the latest version of Python at https://www.python.org/downloads/ or with your operating system’s package man-

ager.

You can verify that Python is installed by typing python from your shell; you should see something like:

Python 3.4.x

[GCC 4.x] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>>

2.2.2 Set up a database

This step is only necessary if you’d like to work with a “large” database engine like PostgreSQL, MySQL, or Oracle.

To install such a database, consult the database installation information.

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2.2.3 Remove any old versions of Django

If you are upgrading your installation of Django from a previous version, you will need to uninstall the old Django

version before installing the new version.

2.2.4 Install Django

You’ve got three easy options to install Django:

• Install an ofﬁcial release. This is the best approach for most users.

• Install a version of Django provided by your operating system distribution.

• Install the latest development version. This option is for enthusiasts who want the latest-and-greatest features

and aren’t afraid of running brand new code. You might encounter new bugs in the development version, but

reporting them helps the development of Django. Also, releases of third-party packages are less likely to be

compatible with the development version than with the latest stable release.

Always refer to the documentation that corresponds to the version of Django you’re using!

If you do either of the ﬁrst two steps, keep an eye out for parts of the documentation marked new in development

version. That phrase ﬂags features that are only available in development versions of Django, and they likely won’t

work with an ofﬁcial release.

2.2.5 Verifying

To verify that Django can be seen by Python, type python from your shell. Then at the Python prompt, try to import

Django:

>>> import django

>>> print(django.get_version())

2.0

You may have another version of Django installed.

2.2.6 That’s it!

That’s it – you can now move onto the tutorial.

2.3 Writing your ﬁrst Django app, part 1

Let’s learn by example.

Throughout this tutorial, we’ll walk you through the creation of a basic poll application.

It’ll consist of two parts:

• A public site that lets people view polls and vote in them.

• An admin site that lets you add, change, and delete polls.

We’ll assume you have Django installed already. You can tell Django is installed and which version by running the

following command in a shell prompt (indicated by the $ preﬁx):

2.3. Writing your ﬁrst Django app, part 1 13

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$ python -m django --version

If Django is installed, you should see the version of your installation. If it isn’t, you’ll get an error telling “No module

named django”.

This tutorial is written for Django 2.0, which supports Python 3.4 and later. If the Django version doesn’t match, you

can refer to the tutorial for your version of Django by using the version switcher at the bottom right corner of this

page, or update Django to the newest version. If you’re using an older version of Python, check What Python version

can I use with Django? to ﬁnd a compatible version of Django.

See How to install Django for advice on how to remove older versions of Django and install a newer one.

Where to get help:

If you’re having trouble going through this tutorial, please post a message to django-users or drop by #django on

irc.freenode.net to chat with other Django users who might be able to help.

2.3.1 Creating a project

If this is your ﬁrst time using Django, you’ll have to take care of some initial setup. Namely, you’ll need to auto-

generate some code that establishes a Django project – a collection of settings for an instance of Django, including

database conﬁguration, Django-speciﬁc options and application-speciﬁc settings.

From the command line, cd into a directory where you’d like to store your code, then run the following command:

$ django-admin startproject mysite

This will create a mysite directory in your current directory. If it didn’t work, see Problems running django-admin.

Note: You’ll need to avoid naming projects after built-in Python or Django components. In particular, this means

you should avoid using names like django (which will conﬂict with Django itself) or test (which conﬂicts with a

built-in Python package).

Where should this code live?

If your background is in plain old PHP (with no use of modern frameworks), you’re probably used to putting code

under the Web server’s document root (in a place such as /var/www). With Django, you don’t do that. It’s not a

good idea to put any of this Python code within your Web server’s document root, because it risks the possibility that

people may be able to view your code over the Web. That’s not good for security.

Put your code in some directory outside of the document root, such as /home/mycode.

Let’s look at what startproject created:

mysite/

manage.py

mysite/

__init__.py

settings.py

urls.py

wsgi.py

These ﬁles are:

14 Chapter 2. Getting started

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